Plasma prekallikrein (PKK) is the precursor of plasma kallikrein (PK), which is encoded by the KLKB1 gene. PKK is a glycoprotein that participates in the surface-dependent activation of blood coagulation, fibrinolysis, kinin generation, and inflammation. PKK is converted to PK by Factor XIIa by the cleavage of an internal Arg-Ile peptide bond. PK liberates kinins from kininogens and also generates plasmin from plasminogen. PK is a member of the kinin-kallikrein pathway, which consists of several proteins that play a role in inflammation, blood pressure control, coagulation, and pain.